Evaluating Root Cause Analysis Processes
Are you evaluating root cause analysis processes? If so, this page looks at the pros and cons of five common root cause analysis approaches.
Organizations use a variety of approaches to find the root causes of problems. In turn, evaluating which root cause analysis process to use is important. The most popular, formal approach is probably the fishbone, or Ishikawa, diagram. This approach has been in use for at least 50 years. It includes use of the ‘5 Why’ process to build out possible causes on each bone.
The ‘5 Why’ technique came more into vogue with the growth in popularity of lean manufacturing and six sigma methodologies. This tool has been in use since 1980, if not before. To note, it is part of the Toyota Production System model. Unfortunately, few organizations truly master the skills one needs to (1) find the root causes of their problems and (2) implement fundamental system changes to address those causes. In turn, they continue to face the same issues day in and day out. Their problems continue over time.
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What are the Most Common Root Cause Analysis Processes?
This page looks at the similarities and differences between five common techniques organizations use for root cause analysis – the 5 Whys, Kepner-Tregoe Problem Analysis, fishbone or Ishikawa diagrams, change analysis, fault tree analysis – and the TapRooT® root cause analysis process.
For help in evaluating root cause analysis processes, I discuss these techniques below. Then, I present a summary of the eight advantages the TapRooT® root cause analysis process provides. You get to decide which approach might work the best for you.
Evaluating Root Cause Analysis Options: 5 Whys
5 Why Features:
From my perspective, the Five Whys represent more of a conceptual, versus a systematic, fact-driven approach, to root cause analysis. It was adopted from the Japanese approach to management, and most notably practiced by Mr. Shigeo Shingo. Shingo would use the five whys on the production floor when he would tour manufacturing sites. In essence, Mr. Shingo would continue to ask why five or more times to get to the true cause of a problem. His questions were structured to help lead the employees he was talking to towards the problem’s source.
5 Why Advantages:
If a person knows how to ask good, successive ‘why’ questions, and is able to ask them of the right people, he or she will find at least one root cause for a given problem. This approach takes little time to perform. One needs as few as five minutes to perform a ‘5 Why’ analysis. It does not require the use of special software, flip chart paper, or reading materials. Performing the process repeatedly with the same group of people in a sound manner can lead to a new way of thinking amongst those people that have been exposed to the tool’s use.
5 Why Disadvantages:
The 5 Why approach normally leads to the identification of just one root cause for the problem in question. You will need to go through the ‘5 Why’ process several times for a given problem in order to identify all root causes. To do so effectively requires even more skill of the part of the question asker. It also does not necessarily point the problem solver towards the generic causes of similar problems.
This approach requires significant skill in order to learn how to ask the right why questions. The ‘5 Why’ technique is not as simple as asking ‘why?’ five times. The use of this tool will lead to the definition of a root cause that is also a necessary change (a corrective action). The 5 Why process does not often result in a sound set of corrective actions. Most people fail to gain much success when they use this tool. This is often because they cannot develop the ability to ask good, successive ‘why’ questions. Mr. Shingo could do so with skill, but few others can.
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Evaluating Root Cause Analysis Options: Kepner Tregoe Problem Analysis
Problem Analysis Features:
I attended a five-day KT training course in 1990. The training did cover root cause analysis in a sense, but more in the form of general problem analysis. The key components of the KT process include problem analysis, potential problem analysis, situation analysis, and decision analysis. Problem analysis contains a form of root cause analysis, but is based largely on the ‘is / is not’ tool that is more similar to the TapRooT® Change Analysis process. The Decision Analysis tool is a great tool, and I still advocate its use today. It helps people evaluate possible improvement options in a systematic, fact-based manner more than find root causes. Use Situation Analysis to assess the risk associated with possible improvements, and Potential Problem Analysis to look at the possible repercussions of failing to make a change.
Problem Analysis Advantages:
Like TapRooT®, if the user performs a good problem investigation and collects a lot of information (especially data), they can find the causes of the specific problem. These problems might not be specifically called root causes. To me, the Decision Analysis tool is one of the best out there for evaluating improvement options (possible corrective actions).
Problem Analysis Disadvantages:
Good information and a formal evaluation process helps keep the user of any of these tools from focusing too much on blaming people. Tool use can consume lots of time, however. They also may be as functional as TapRooT® is in terms of getting to generic causes. I also question whether or not these tools can help you get to the true system problems that are causing given incidents to occur (which the TapRooT® process is designed to help you do). Well-rounded corrective action development is really not a focus of these tools as I remember them.
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Evaluating Root Cause Analysis Options: Fault Tree Analysis
Fault Tree Features:
My perspective of fault trees is that they encourage the user to (1) ask the five whys multiple times for a given type of problem and (2) evaluate several possible problem causes on one diagram. This is similar to the manpower, methods, materials, and machines boxes on a fishbone diagram. Like the other common root cause analysis approaches, fault trees are more of an opinion-based tool. Failure mode type and probabilities help you create the tree branches, but no predetermined questions exist.
Fault Tree Analysis Advantages:
From my perspective, I prefer fault trees over fishbone diagrams. Their design allows the user to identify four to five levels of ‘why’ for a given problem, if the users exercise a high level of discipline as they draw their charts. I use fault trees to to troubleshoot persistent problems, such as quality defects. Problems that won’t go away tend to have a common set of causes and sub-causes. A fault tree is similar to the TapRooT® Equifactor tree that one uses to troubleshoot equipment issues.
Fault Tree Disadvantages:
Fault trees typically fail for one of three reasons. First, people do not use them in a disciplined manner to develop multiple problem causes at each level. Second, one must sort through multiple levels of potential causes for each problem type. Third, fault tree results can be opinion driven. They often tend to be a blend of a cause effect diagram and a flow chart. In such cases, the user can easily get lost and not arrive at any particular root cause.
Also, a well-developed fault tree often leads the user to discover that the same management systems (such as poor training, employee turnover, weak communications, and poor procedure design) are at the root of their problems. This is similar to TapRooT® generic causes. A well-designed fault tree may lead you to the TapRooT® basic cause categories. However, its use rarely leads to a comprehensive mix of TapRooT® root causes.
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